Capillaries reach into almost all tissues of the human body and supply tissues with oxygen and nutrients as well as removing harmful waste products. Under typical conditions, the endothelial cells lining capillaries do not divide, and capillaries, therefore, do not normally increase in number or size in a human adult. Under certain normal conditions, however, such as when a tissue is damaged, or during certain parts of the menstrual cycle, capillaries begin to proliferate rapidly. This process of forming new capillaries from pre-existing blood vessels is known as angiogenesis or neovascularization. See Folkman, J. Scientific American 275, 150–154 (1996). Angiogenesis during wound healing is an example of pathophysiological neovascularization during adult life. During wound healing, the additional capillaries provide a supply of oxygen and nutrients, promote granulation tissue, and aid in waste removal. After termination of the healing process, the capillaries normally regress. Lymboussaki, A. “Vascular Endothelial Growth Factors and their Receptors in Embryos, Adults, and in Tumors” Academic Dissertation, University of Helsinki, Molecular/Cancer Biology Laboratory and Department of Pathology, Haartman Institute, (1999).
Angiogenesis also plays an important role in the growth of cancer cells. It is known that once a nest of cancer cells reaches a certain size, roughly 1 to 2 mm in diameter, the cancer cells must develop a blood supply in order for the tumor to grow larger as diffusion will not be sufficient to supply the cancer cells with enough oxygen and nutrients. A compound that inhibits angiogenesis will thus act to retard or halt the growth of cancer cells.
Receptor tyrosine kinases (RTKs) are polypeptides that regulate developmental cell growth and differentiation and remodeling and regeneration of adult tissues. Mustonen, T. et al., J. Cell Biology 129, 895–898 (1995); van der Geer, P. et al. Ann Rev. Cell Biol. 10, 251–337 (1994). Polypeptide ligands known as growth factors or cytokines, are known to activate RTKs. Signaling involves ligand binding and a shift in conformation in the external domain of the receptor resulting in its dimerization. Lymboussaki, A. “Vascular Endothelial Growth Factors and their Receptors in Embryos, Adults, and in Tumors” Academic Dissertation, University of Helsinki, Molecular/Cancer Biology Laboratory and Department of Pathology, Haartman Institute, (1999); Ullrich, A. et al., Cell 61, 203–212 (1990). Binding of the ligand to the RTK results in receptor trans-phosphorylation at specific tyrosine residues and activation of the catalytic domains for the phosphorylation of cytoplasmic substrates. Id.
Two subfamilies of RTKs are specific to the vascular endothelium. These include the VEGF subfamily and the Tie receptor subfamily. Class III RTKs include VEGFR-1, VEGFR-2, and VEGFR-3. Shibuya, M. et al., Oncogene 5, 519–525 (1990); Terman, B. et al., Oncogene 6, 1677–1683 (1991); Aprelikova, O. et al., Cancer Res. 52, 746–748 (1992).
A number of substances have been identified that promote angiogenesis. These include angiopoietin-1, basic fibroblast growth factor (bFGF) and vascular endothelial growth factor (VEGF). VEGF was first described as a protein able to induce vascular permeability and endothelial cell proliferation and was identified as a major inducer of angiogenesis and vasculogenesis. Ferrara, N. et al., Endocrinol. Rev. 18, 4–25 (1997). VEGF is known to specifically bind to RTKs including VEGFR-1 and VEGFR-2. DeVries, C. et al., Science 255, 989–991 (1992); Quinn, T. et al., Proc. Natl. Acad. Sci. 90, 7533–7537 (1993). It is now known that VEGF stimulates the migration and proliferation of endothelial cells and induces angiogenesis both in vitro and in vivo. Connolly, D. et al., J. Biol. Chem. 264, 20017–20024 (1989); Connolly, D. et al., J. Clin. Invest. 84, 1470–1478 (1989); Ferrara, N. et al., Endocrino. Rew. 18, 4–25 (1997); Leung, D. et al., Science 246, 1306–1309 (1989); Plouet, J. et al., EMBO J 8, 3801–3806 (1989).
Because angiogenesis is known to be critical to the growth of cancer and to be controlled by VEGF and VEGF-RTK, substantial efforts have been undertaken to develop compounds which inhibit or retard angiogenesis and inhibit VEGF-RTK.
Platelet derived growth factor receptor kinase (PDGFRK) is another type of RTK. PDGF expression has been shown in a number of different solid tumors, from glioblastomas to prostate carcinomas. In these various tumor types, the biologicical role of PDGF signaling can vary from autocrine stimulation of cancer cell growth to more subtle paracrine interactions involving adjacent stroma and angiogenesis. Therefore, inhibiting the PDGFR kinase activity with small molecules may interfere with tumor growth and angiogenesis.
Tie-2 is a membrane RTK. Upon binding to its ligand, Tie-2 is activated and phosphorylates its downstream signal proteins. Tie-2 kinase activity may then trigger a pathway of cellular response that leads to stabilization of vascular vessels in cancer. Therefore, blocking kinase activity of Tie-2, in synergy with blockage of activity of other angiogenic kinases such as VEGF and bFGF receptor kinases, may be effective in cutting off the blood supply to cancer cells and in treating the disease.
Glycogen synthase kinase 3 (GSK-3) is a serine/threonine kinase for which two isoforms, α and β, have been identified. Woodgett, Trends Biochem. Sci., 16:177–81 (1991). Both GSK-3 isoforms are constitutively active in resting cells. GSK-3 was originally identified as a kinase that inhibits glycogen synthase by direct phosphorylation. Upon insulin activation, GSK-3 is inactivated, thereby allowing the activation of glycogen synthase and possibly other insulin-dependent events, such glucose transport. Subsequently, it has been shown that GSK-3 activity is also inactivated by other growth factors that, like insulin, signal through receptor tyrosine kinases (RTKs). Examples of such signaling molecules include IGF-1 and EGF. Saito et al., Biochem. J., 303:27–31 (1994); Welsh et al., Biochem. J. 294:625–29 (1993); and Cross et al., Biochem. J., 303:21–26 (1994).
Agents that inhibit GSK-3 activity are useful in the treatment of disorders that are mediated by GSK-3 activity. In addition, inhibition of GSK-3 mimics the activation of growth factor signaling pathways and consequently GSK-3 inhibitors are useful in the treatment of diseases in which such pathways are insufficiently active. Examples of diseases that can be treated with GSK-3 inhibitors are described below.
Type 2 diabetes is an increasingly prevalent disease of aging. It is initially characterized by decreased sensitivity to insulin and a compensatory elevation in circulating insulin concentrations, the latter of which is required to maintain normal blood glucose levels. Increased insulin levels are caused by increased secretion from the pancreatic beta cells, and the resulting hyperinsulinemia is associated with cardiovascular complications of diabetes. As insulin resistance worsens, the demand on the pancreatic beta cells steadily increases until the pancreas can no longer provide adequate levels of insulin, resulting in elevated levels of glucose in the blood. Ultimately, overt hyperglycemia and hyperlipidemia occur, leading to the devastating long-term complications associated with diabetes, including cardiovascular disease, renal failure and blindness. The exact mechanism(s) causing type 2 diabetes are unknown, but result in impaired glucose transport into skeletal muscle and increased hepatic glucose production, in addition to inadequate insulin response. Dietary modifications are often ineffective, therefore the majority of patients ultimately require pharmaceutical intervention in an effort to prevent and/or slow the progression of the complications of the disease. Many patients can be treated with one or more of the many oral anti-diabetic agents available, including sulfonylureas, to increase insulin secretion. Examples of sulfonylurea drugs include metformin for suppression of hepatic glucose production, and troglitazone, an insulin-sensitizing medication. Despite the utility of these agents, 30–40% of diabetics are not adequately controlled using these medications and require subcutaneous insulin injections. Additionally, each of these therapies has associated side effects. For example, sulfonylureas can cause hypoglycemia and troglitazone can cause severe hepatoxicity. Presently, there is a need for new and improved drugs for the treatment of prediabetic and diabetic patients.
As described above, GSK-3 inhibition stimulates insulin-dependent processes and is consequently useful in the treatment of type 2 diabetes. Recent data obtained using lithium salts provides evidence for this notion. The lithium ion has recently been reported to inhibit GSK-3 activity. Klein et al., PNAS 93:8455–9 (1996). Since 1924, lithium has been reported to have antidiabetic effects including the ability to reduce plasma glucose levels, increase glycogen uptake, potentiate insulin, up-regulate glucose synthase activity and to stimulate glycogen synthesis in skin, muscle and fat cells. However, lithium has not been widely accepted for use in the inhibition of GSK-3 activity, possibly because of its documented effects on molecular targets other than GSK-3. The purine analog 5-iodotubercidin, also a GSK-3 inhibitor, likewise stimulates glycogen synthesis and antagonizes inactivation of glycogen synthase by glucagon and vasopressin in rat liver cells. Fluckiger-Isler et al., Biochem J. 292:85–91 (1993); and Massillon et al., Biochem J. 299:123–8 (1994). However, this compound has also been shown to inhibit other serine/threonine and tyrosine kinases. Massillon et al., Biochem J. 299:123–8 (1994).
GSK-3 is also involved in biological pathways relating to Alzheimer's disease (AD). The characteristic pathological features of AD are extracellular plaques of an abnormally processed form of the amyloid precursor protein (APP), so called β-amyloid peptide (β-AP) and the development of intracellular neurofibrillary tangles containing paired helical filaments (PHF) that consist largely of hyperphosphorylated tau protein. GSK-3 is one of a number of kinases that have been found to phosphorylate tau protein in vitro on the abnormal sites characteristic of PHF tau, and is the only kinase also demonstrated to do this in living cells and in animals. Lovestone et al., Current Biology 4:1077–86 (1994); and Brownlees et al., Neuroreport 8: 3251–3255 (1997). Furthermore, the GSK-3 kinase inhibitor, LiCl, blocks tau hyperphosphorylation in cells. Stambolic et al., Current Biology 6:1664–8 (1996). Thus GSK-3 activity may contribute to the generation of neurofibrillary tangles and consequently to disease progression. Recently it has been shown that GSK-3β associates with another key protein in AD pathogenesis, presenillin 1 (PS1). Takashima et., PNAS 95:9637–9641(1998). Mutations in the PS1 gene lead to increased production of β-AP, but the authors also demonstrate that the mutant PS1 proteins bind more tightly to GSK-3β and potentiate the phosphorylation of tau, which is bound to the same region of PS1.
It has also been shown that another GSK-3 substrate, β-catenin, binds to PS1. Zhong et al., Nature 395:698–702 (1998). Cytosolic β-catenin is targeted for degradation upon phosphorylation by GSK-3 and reduced β-catenin activity is associated with increased sensitivity of neuronal cells to β-AP induced neuronal apoptosis. Consequently, increased association of GSK-3β with mutant PS1 may account for the reduced levels of β-catenin that have been observed in the brains of PS1-mutant AD patients and to the disease related increase in neuronal cell-death. Consistent with these observations, it has been shown that injection of GSK-3 antisense but not sense, blocks the pathological effects of β-AP on neurons in vitro, resulting in a 24 hour delay in the onset of cell death and increased cell survival at 1 hr from 12 to 35%. Takashima et al., PNAS 90:7789–93. (1993). In these latter studies, the effects on cell-death are preceded (within 3–6 hours of β-AP administration) by a doubling of intracellular GSK-3 activity, suggesting that in addition to genetic mechanisms that increase the proximity of GSK-3 to its substrates, β-AP may actually increase GSK-3 activity. Further evidence for a role for GSK-3 in AD is provided by the observation that the protein expression level (but, in this case, not specific activity) of GSK-3 is increased by 50% in postsynaptosomal supernatants of AD vs. normal brain tissue. Pei et al., J. Neuropathol Exp., 56:70–78 (1997). Thus, specific inhibitors of GSK-3 should slow the progression of Alzheimer's Disease.
In addition to the effects of lithium described above, there is a long history of the use of lithium to treat bipolar disorder (manic depressive syndrome). This clinical response to lithium may reflect an involvement of GSK-3 activity in the etiology of bipolar disorder, in which case GSK-3 inhibitors could be relevant to that indication. In support of this notion it was recently shown that valproate, another drug commonly used in the treatment of bipolar disorder, is also a GSK-3 inhibitor. Chen et al., J. Neurochemistry, 72:1327–1330 (1999). One mechanism by which lithium and other GSK-3 inhibitors may act to treat bipolar disorder is to increase the survival of neurons subjected to aberrantly high levels of excitation induced by the neurotransmitter, glutamate. Nonaka et al., PNAS 95: 2642–2647 (1998). Glutamate-induced neuronal excitotoxicity is also believed to be a major cause of neurodegeneration associated with acute damage, such as in cerebral ischemia, traumatic brain injury and bacterial infection. Furthermore it is believed that excessive glutamate signaling is a factor in the chronic neuronal damage seen in diseases such as Alzheimer's, Huntingdon's, Parkinson's, AIDS associated dementia, amyotrophic lateral sclerosis (AML) and multiple sclerosis (MS). Thomas, J. Am. Geriatr. Soc. 43: 1279–89 (1995). Consequently, GSK-3 inhibitors should provide a useful treatment in these and other neurodegenerative disorders.
GSK-3 phosphorylates transcription factor NF-AT and promotes its export from the nucleus, in opposition to the effect of calcineurin. Beals et al., Science 275:1930–33 (1997). Thus, GSK-3 blocks early immune response gene activation via NF-AT, and GSK-3 inhibitors may tend to permit or prolong activation of immune responses. Thus, GSK-3 inhibitors are believed to prolong and potentiate the immunostimulatory effects of certain cytokines, and such an effect may enhance the potential of those cytokines for tumor immunotherapy or indeed for immunotherapy in general.
Lithium has other biological effects. It is a potent stimulator of hematopoiesis, both in vitro and in vivo. Hammond et al., Blood 55: 26–28 (1980). In dogs, lithium carbonate eliminated recurrent neutropenia and normalized other blood cell counts. Doukas et al. Exp. Hematol. 14: 215–221 (1986). If these effects of lithium are mediated through the inhibition of GSK-3, GSK-3 inhibitors may have even broader applications. Since inhibitors of GSK-3 are useful in the treatment of many diseases, the identification of new inhibitors of GSK-3 would be highly desirable.
NEK-2 is a mammalian serine threonine kinase, which is structurally related to the NimA kinase from the fungus Aspergillus nidulans. Mutations in NimA result in G2 phase arrest of cells and overexpression of wt NimA results in premature chromatin condensation, even when ectopically expressed in mammalian cells. Both protein and kinase levels peak in S/G2 phase of the cell cycle. NimA also appears to be required for the localization of cdk1/cyclinB complex to the nucleus and spindle pole body. Histone H3 has been shown to be an in vitro substrate for the kinase, and if this is also the case in vivo, it may explain the role of the kinase in chromosome condensation. Six NimA kinases have been identified to date in mammals, and of these, NEK-2 appears to be the most closely related to NimA. It's activity is also cell cycle regulated, peaking in S/G2 phase. Overexpression of NEK-2, however, does not affect chromatin condensation but instead results in a pronounced splitting of centrosomes, possibly due to the loss of centriole/centriole adhesion. There is evidence that NEK-2 is regulated by phosphorylation and can interact with protein phosphatase PP1. NEK-2 is ubiquitously expressed and appears to be most abundant in testis. Hyseq cluster 374113, containing only NEK-2 sequences shows dramatic overexpression of NEK-2 in lymph node metastasis (13.3×) and in primary tumor (6.5×). Inhibition of NEK-2 by antisense oligonucleotides inhibited cell proliferation and reduced the capability of cells to grow in soft agar. In addition, increased cell death was observed in these cells both in the presence and absence of cisplatin.
Ultraviolet light, ionizing radiation, environmental agents and cytotoxic drugs can result in damage to cellular DNA integrity. When such damage occurs during DNA replication or cell division it is potentially catastrophic and may result in cell death. The cellular response is to arrest the cell cycle at one of two checkpoints (G1/S or G2/M) to either permit DNA repair or initiate apoptosis.

The G1/S checkpoint is regulated by the p53 transcriptional activator protein and the absence of this critical protein is often an important step in tumorigenesis, thus defining p53 as a tumor suppressor. In fact, nearly 50% of all cancers are p53 defective due to mutation. T. Soussi, Ann. N.Y. Acad Sci., 910, 121 (2001). In response to DNA damage, checkpoint kinase 2 (CHK-2) phosphorylates p53 and this results in stabilization of the protein and an elevation in p53 levels. A. Hirao et al., Science, 287, 1824 (2000). Consequently, negative cell cycle regulators, such as p21Waf1/Cip1, are activated and halt the cell cycle at the G1/S checkpoint. B. Vogelstein et al., Nature, 408, 307 (2000).
The G2/M checkpoint is monitored by the serine/threonine checkpoint kinase 1 (CHK-1). Upon DNA damage, the protein kinase ATR (ataxia-telangiectasia mutated—rad53 related kinase) is activated. H. Zhao et al., Mol. Cell Biol., 21, 4129 (2001); Q. Liu et al., Genes Dev., 14, 1448 (2000). SATR-dependent phosphorylation of CHK-1 promotes its phosphorylation of cdc25 and Wee1 and ultimately inactivation of cdc 2. Thus, CHK-1 phosphorylation of cdc25c targets it for nuclear export to the cytoplasm and as a result the cdc25c phosphatase is rendered unavailable to activate cdc 2 by dephosphorylation. Y. Sanchez et al., Science, 277, 1497 (1997); C. Y. Peng et al., Science, 277, 1501 (1997); T. A. Chen et al., Nature, 401, 616 (1999); and A. Lopez-Girona et al., Nature, 397, 172 (1999). In addition, CHK-1 activates the protein kinase Weel, which phosphorylates and inactivates cdc 2. J. Lee et al. Mol. Biol. Cell, 12, 551 (2001); L. L. Parker et al., Science, 257, 1955 (1992). These dual pathways thus converge to result in cell cycle arrest. Because cell cycle arrest is a potential mechanism by which tumor cells can overcome the damage induced by cytotoxic agents, abrogation of these checkpoints with novel therapeutic agents should increase the sensitivity of tumors to chemotherapy. The presence of two checkpoints, coupled with the tumor specific abrogation of one of these by p53 mutations in 50% of cancers, can be exploited to design tumor-selective agents. Thus, in p53 minus tumors, therapeutic inhibition of G2/M arrest leaves cancerous cells no options for DNA damage repair and results in apoptosis. Normal cells have wild type p53 and retain an intact G1/S checkpoint. Thus these cells have an opportunity to correct DNA damage and survive. One approach to the design of chemosensitizers that abrogate the G2/M checkpoint is to identify inhibitors of the key G2/M regulatory kinase, CHK-1.

The synthesis of various quinoline derivatives is disclosed in WO 97/48694. These compounds are disclosed as capable of binding to nuclear hormone receptors and being useful for stimulating osteoblast proliferation and bone growth. The compounds are also disclosed as being useful in the treatment or prevention of diseases associated with nuclear hormone receptor families.
Various quinoline derivatives in which the benzene ring of the quinolone is substituted with a sulfur group are disclosed in WO 92/18483. These compounds are disclosed as being useful in pharmaceutical formulations and as medicaments.
Various indolyl substituted compounds have recently been disclosed in WO 01/29025, and various benzimidazolyl substituted compounds have recently been disclosed in WO 01/28993. Such compounds are reportedly capable of inhibiting, modulating and/or regulating signal transduction of both receptor-type and non-receptor type tyrosine kinases. Neither of the PCT publications discloses benzimidazole-substituted indazoles.
Various indazole compounds and pharmaceutical formulations containing them are disclosed in WO 01/02369 and recently published WO 01/53268. Such compositions are purportedly useful for mediating tyrosine kinase signal transduction and thereby modulating and/or inhibiting cell proliferation. Some of the disclosed compounds include the benzimidazole group. Various benzimidazoles substituted with —C(═O)—NH2 are disclosed in WO 00/68206 as useful as inhibitors of the enzyme poly(ADP-ribose)polymerase and for use in producing medicaments.
A continuing need exists for compounds that inhibit the proliferation of capillaries, inhibit the growth of tumors, treat cancer, treat diabetes, stimulate insulin-dependent processes, treat Alzheimer's disease, treat central nervous system disorders, prolong immune responses, reduce the splitting of centrosomes, block DNA repair, modulate cell cycle arrest, and/or inhibit enzymes such as flt-1 (VEGFR2), KDR (VEGFR2), Flk-1, bFGFR, GSK-3, NEK-2, CHK-1, Tie-2, PDGF, and cdc 2, and pharmaceutical formulations and medicaments that contain such compounds. A need also exists for methods for administering such compounds, pharmaceutical formulations, and medicaments to patients or subjects in need thereof.